JP2002216397A - Optical disk and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small-sized optical disk with a large recording capacity which is small in eccentricity and can be equipped to a driving device of conventional constitution. SOLUTION: As for the optical disk 10, a projection 12 having a center hole 11 is formed at the center of a face where the recording layer 16 of a substrate 13 is not held, and the recording layer 16 extends from the center of a face where the recording layer 16 of the substrate 13 is held to the outer circumference. As for the manufacturing method of the optical disk, a fixed mold 21 having a fixed mirror 21a, a hot-runner composing material 22 provided at the central part of the fixed mirror 21a, a movable mold 23 having a movable mirror 23a, a stamper 24 and a stamper-positioning pin 25 arranged on the movable mirror 23a and a outer circumferential ring 26 are provided, and the substrate 13 is molded by using the mold in which a cavity 27 for molding a substrate is formed by the fixed mirror 21a, the hot-runner composing material 22, the stamper 24, the stamer-positioning pin 25 and the outer circumferential ring 26.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk and a method of manufacturing the same, and more particularly, to the structure of a first surface type optical disk in which information is recorded, reproduced or erased by irradiating light from a recording layer forming surface side. And its manufacturing method.

[0002]

2. Description of the Related Art In recent years, with the rapid progress of computerization in society, in order to store and carry enormous amounts of information, higher storage capacity and smaller size of storage devices are more strongly required. ing.

[0003] In the field of optical discs as well, mainly as recording media for digital cameras and digital movies,
2 inch size magneto-optical disk or 8 cm size D
Optical disk standards such as VD-RAM have already been proposed, and furthermore, there is a need for the development of an optical disk that can be mounted on a mobile phone, is smaller and lighter, and can respond to demands for power saving.

In order to put such a high-capacity and small-sized optical disk to practical use, it is essential to use the disk size effectively. However, as illustrated in FIGS. 10 and 11, the conventional optical disc 1 has a configuration in which a center hub 3 having a centering hole 3a and a magnetic plate 3b is fixed to the center of a ring-shaped substrate 2 having a center hole 2a. Therefore, the recording layer 4 cannot be formed in the setting portion of the center hub 3, and the central area of the optical disc cannot be effectively used. Although an optical disk without the center hub 3 is conventionally known, even in this type of optical disk, since the center hole 2a as a centering hole is formed in the center of the substrate 1, the center area of the optical disk is also required. It cannot be used effectively.

[0005] On the other hand, the format of a drive device for recording, reproducing or erasing information by mounting an optical disk 1 is shown in FIG.
0, a recording / reproducing light 5a is radiated to the recording layer 4 from the optical head 5 disposed on the substrate 2 side via the substrate 2, as shown in FIG. Recording / reproducing light 5a directly from the optical head 5 to the recording layer 4
In the drive device shown in FIG. 10, the moving range of the optical head 5 is limited by the spindle 6 and the turntable 7 for driving the optical disc 1 to rotate. The disk cannot be moved to a position facing the central area, and the disk size cannot be used effectively. On the other hand, in the drive device shown in FIG. 11, the moving range of the optical head 5 is not limited by the spindle 6 and the turntable 7, and the optical head 5 can be moved to a position facing the central area of the optical disk 1. It is more advantageous than the drive device of FIG. Reference numeral 7a in the figure denotes a magnet that is installed on the turntable 7 and attracts the magnetic plate 3b provided on the center hub 3 to clamp the optical disk 1 on the turntable 7, and reference numeral 8 denotes an optical head 5 2 shows a head carriage for transferring the data in the radial direction of the optical disc 1.

In order to solve the problem that the central area of the optical disk cannot be used effectively, for example, Japanese Patent Application Laid-Open No.
In Japanese Patent Publication No. 2 (1993), a substrate is formed in a disc shape having no center hole, and grooves and pits are formed concentrically or spirally from the center to the outer periphery of the substrate. An optical disc having a recording layer formed on a pit formation surface is disclosed. According to the optical disk of this configuration, since information can be recorded up to the center of the substrate, the disk size can be effectively used to the maximum, and the recording capacity can be increased and the disk size can be reduced.

[0007]

However, the optical disk according to the above-mentioned known example does not have a center hole at the center of the substrate and has a configuration in which the optical disk is centered by using the outer periphery of the substrate. In order to suppress the eccentricity of the track with respect to the center within an allowable range, it is necessary to match the center of the track with the center of the board with high accuracy, but it is not possible to match the center of the track with the center of the board with high accuracy. Since it is extremely difficult in practice, there is a problem that it is difficult to manufacture a good product with a good yield. In addition, since the turntable becomes larger and the spindle motor becomes larger accordingly, there is a problem that the drive device becomes larger, the cost increases, and the power consumption of the drive device increases.

An object of the present invention is to solve such a technical problem, and an object of the present invention is to provide an optical disk which can be mounted on a conventional drive device with a small size, a high recording capacity and a small track eccentricity. And a method of manufacturing the same.

[0009]

According to the present invention, there is provided an optical disk having a recording layer carried on one side of a substrate, wherein the recording layer of the substrate carries the recording layer. A projection having a center hole is formed at the center of the surface on which the recording layer is not formed, and the substrate is flat from the center to the outer periphery of the surface on which the recording layer is carried.

[0010] As described above, when the recording layer is flattened from the center to the outer periphery of the recording layer supporting surface of the substrate, the central area of the optical disk, which could not be used as a conventional information recording area, can be effectively used. And the disk size can be reduced. Further, when a projection having a center hole is formed at the center of the surface of the substrate on which the recording layer is not supported, the signal pattern formed on the recording layer supporting surface of the substrate is formed with reference to the center of the substrate. By inserting the spindle, track centering can be performed with high accuracy. Further, when a projection having a center hole is formed at the center of the substrate, it can be mounted on a drive device having a conventional configuration including a spindle and a turntable fixed to the spindle and supporting only the inner peripheral area of the optical disc. In addition, it is not necessary to largely modify the drive device.

The present invention relates to an optical disk.
The diameter of the center hole in the first problem solving means is
It was configured to be formed to 0.8 mm to 3 mm.

The allowable eccentricity between the center of the spindle and the center of the track is generally about 10 μm to 20 μm. However, in order to realize a high-density disk, the eccentricity is preferably about 5 μm to 10 μm. According to experiments, there is a correlation between the amount of eccentricity and the diameter of the spindle that rotates with the optical disk mounted. In order to keep the amount of eccentricity within the above range, it is desirable that the diameter of the spindle be 3 mm or less. It turns out. It is preferable to use the spindle of the spindle motor as the spindle in order to simplify the configuration of the drive device, reduce the cost, and reduce the size. However, if the diameter of the spindle of the spindle motor is 0.8 mm or less, it is necessary to use the spindle. High rigidity cannot be secured. Therefore, the diameter of the center hole formed in the substrate is set to 0.8 mm to 3 m.
When it is formed to m, the eccentricity between the center of the spindle and the center of the track can be kept within an allowable range while securing the rigidity of the spindle.

The present invention relates to an optical disk.
In the first problem solving means, a magnetic plate is provided on the surface of the substrate on which the protrusions are formed.

As described above, when the magnetic plate is provided on the surface of the substrate on which the protrusions are formed, an optical disk of a magnet clamp system can be configured without reducing the recording area.

The present invention relates to an optical disk.
The magnetic plate in the third means for solving the problems is fixed by a projection formed on the substrate.

As described above, if the magnetic plate for the magnet clamp is fixed by the projection formed on the substrate, it is not necessary to form a special member for fixing the magnetic plate on the substrate.
It is possible to configure a magnet clamp type optical disk that has a simple substrate structure, is easy to manufacture, and has an excellent appearance.

On the other hand, the present invention relates to a method for manufacturing an optical disk in order to solve the above-mentioned problems. First, after injecting a resin into a substrate molding die to produce a substrate, one side of the obtained substrate is obtained. In a method of manufacturing an optical disc for obtaining a required optical disc by forming a recording layer thereon, a fixed mold having a fixed mirror as the substrate molding mold, and a hot runner forming member provided at a central portion of the fixed mirror, A movable mold having a movable mirror, a stamper disposed on the movable mirror, a stamper positioning pin, and an outer peripheral ring, the fixed mirror, a hot runner forming member,
Using a mold in which a cavity for forming a substrate is formed by a stamper, a stamper positioning pin and an outer ring, a resin is injected into the cavity from a hot runner formed in the hot runner forming member, and the stamper is formed on one surface. The formed signal pattern is transferred, and a substrate having a projection having a center hole at the center of the other surface is obtained.

Thus, a fixed mold having a fixed mirror, a hot runner forming member provided at the center of the fixed mirror, a movable mold having a movable mirror, and a stamper disposed on the movable mirror A fixed mold, a hot runner forming member, a stamper, a mold in which a cavity for forming a substrate is formed by the stamper positioning pin and the outer peripheral ring, and a hot runner. By forming the tip of the forming member into a required shape, a signal pattern is formed on one side, and a substrate having a projection having a center hole formed on the other side can be manufactured integrally. A substrate with projections with small eccentricity between the track and the center hole constituted by That.

The present invention relates to a method of manufacturing an optical disk. Secondly, a resin is injected into a mold for molding a substrate in the first means for solving the above-mentioned problems, and a signal formed on a stamper from the center to the outer periphery of one surface. After obtaining a substrate on which a pattern is transferred and a projection having a center hole at the center of another surface is formed, a magnetic plate is arranged on the surface of the substrate where the projection is formed, and a part of the projection is deformed. Then, the substrate and the magnetic plate are integrated.

Thus, after forming the substrate with the protrusions,
When a magnetic plate is arranged on the surface of the substrate on which the protrusions are formed, and a part of the protrusions is deformed to integrate the substrate and the magnetic plate, a special member for fixing the magnetic plate needs to be formed on the substrate. Therefore, it is possible to easily manufacture a magnet-clamped optical disk having a simple substrate structure and excellent appearance.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, an embodiment of an optical disk according to the present invention will be described with reference to FIGS. FIG. 1 is a cross-sectional view of the optical disc according to the embodiment, FIG. 2 is a cross-sectional view of the optical disc showing a state of attachment to a drive device, and FIG. 3 is a cross-sectional view of the optical disc according to the embodiment in use.

As is clear from FIGS. 1 to 3, the optical disk 10 of this embodiment has a substrate 13 on which a projection 12 having a center hole 11 is formed integrally at the center of one surface, and a projection forming surface of the substrate 13. A magnetic plate 14 is disposed on the side of the substrate 13, and a reflective layer 15, a recording layer 16, and a protective layer 17 carried on a surface of the substrate 13 where the protrusions 12 are not formed. The reflective layer 15, the recording layer 16, and the protective layer 17
The layers are stacked in this order on top.

The substrate 13 is made of a material having a required rigidity such as plastic, glass, ceramic or metal, and is formed in a circular shape having a required size. No center hole 11 is formed in the recording layer supporting surface (the inner surface on which the protrusions 12 are formed) of the substrate 13, and a signal pattern (not shown) is formed concentrically or spirally from the innermost peripheral region to the outermost peripheral region. Is formed. The diameter of the center hole 11 is preferably 0.8 mm to 3 mm in order to suppress the fitting accuracy with the spindle 6 to about 5 μm to 10 μm and to secure the rigidity of the spindle 6.
The amount of protrusion of the projection 12 from the substrate surface is determined by the spindle 6
Accordingly, the optical disk 10 is formed to have a required size for centering, for example, about 0.5 mm to 1.5 mm. The center of the signal pattern (the center of the track) and the center of the center hole 11 are adjusted in the manufacturing process of the substrate 13 so as to match with high accuracy.

The magnetic plate 14 is formed in a ring shape having an inner diameter and an outer diameter substantially the same as the magnet 7a provided on the turntable 7, and is arranged on the surface of the substrate 13 on which the projections 12 are formed. A part of the projection 12 is fixed to the substrate 13. The magnetic layer 14 can be formed of any ferromagnetic material, but is relatively inexpensive and hard to rust.
It is particularly preferable to form with SUS430).

The reflection layer 15 is formed of a single metal having a high reflectance such as gold, silver or aluminum, or an alloy material containing these metals. As the alloy material, Au
-Ag alloy, Au-Ti alloy or Al-Ti alloy is suitable. The reflection layer 15 is formed on substantially the entire surface of one surface of the substrate 13 including the center of the substrate 13.

The recording layer 16 is formed using any known heat mode recording material or photon mode recording material, and is formed over substantially the entire area of one surface of the substrate 13 including the central portion of the substrate 13. 1 to 3, the recording layer 16 is shown as a single layer, but the recording layer 16 may be formed by laminating a plurality of films of the same type or other types as necessary. For example, when the recording layer 16 is made of a magneto-optical recording material, the recording layer 16 can be formed by laminating one or two dielectric films.

The protective layer 17 is for protecting the recording layer 16 from mechanical or chemical adverse effects, and is formed of a dielectric film or a UV resin film. 1 to 3, the protective layer 17 is shown as a single layer, but a plurality of the same type or another type may be used as necessary, for example, by laminating a dielectric film and a UV resin film in two layers. The protective layer 17 may be formed by laminating the above film bodies.

In the optical disk 10 of the present embodiment, the recording layer 16 is formed from the center of the recording layer supporting surface of the substrate 13 to the outer peripheral portion. Therefore, as shown in FIG. By arranging the optical disk 1
The center area of 0 can be effectively used as a recording area, so that the recording capacity of the optical disc can be increased and the disc size can be reduced. Also, the optical disc 1 of the present embodiment
In No. 0, the protrusion 12 having the center hole 11 was formed at the center of the surface of the substrate 13 on which the recording layer 15 was not supported, so that the eccentricity of the track could be regulated with reference to the center hole 11, and the centering of the track could be performed with high precision. And a turntable 7 having a spindle 6 and a turntable 7 fixed to the spindle 6 and supporting only the inner peripheral area of the optical disc 10 can be attached to a conventional drive device. Can be eliminated. Further, in the optical disc 10 of the present example, the diameter of the center hole 11 formed in the substrate 13 is 0.8 mm to 3 m.
m, so that the rigidity of the spindle 6 is secured,
The amount of eccentricity between the center of the spindle and the center of the track can be kept within an allowable range. In addition, the optical disc 10 of the present example
Since the magnetic plate 14 is provided on the surface of the substrate 13 on which the protrusions 12 are formed, an optical disk of the magnet clamp type can be configured without reducing the recording area. in addition,
In the optical disc 10 of this embodiment, the magnetic plate 14 for magnet clamping is fixed by the projections 12 formed on the substrate 13, so that a special member for fixing the magnetic plate 14 is provided on the substrate 13.
Therefore, it is possible to configure a magnet clamp type optical disk which has a simple substrate structure, is easy to manufacture, and is excellent in appearance.

Next, the optical disc 1 according to the above-described embodiment will be described.
0 will be described with reference to FIGS. 4 to 8. 4 is a cross-sectional view of a main part showing a step of injecting the resin into the cavity, FIG. 5 is a cross-sectional view of a main part showing a mold opening step after injection, and FIG. 6 is a cross-sectional view of a main part showing a step of taking out a molded substrate. FIG. 7 is a cross-sectional view showing a process for forming a recording layer or the like on the substrate surface, and FIG. 8 is a cross-sectional view showing a process for attaching a magnetic plate to the substrate.

As shown in FIGS. 4 and 5, a mold for molding a substrate applied to this embodiment is provided at a fixed mold 21 having a fixed mirror 21a and at the center of the fixed mirror 21a. Hot runner forming member 22 and movable mirror 2
The movable mirror 23 includes a movable mold 23 having a movable mirror 3a, a stamper 24, a stamper positioning pin 25, and an outer peripheral ring 26 disposed on the movable mirror 23a.
1a, the hot runner forming member 22, the stamper 24, the stamper positioning pin 25, and the outer peripheral ring 26 form a cavity 27 for molding a substrate.

The hot runner forming member 22 is provided with a runner 22a and a heater 2 around the runner 22a.
2b is buried, so that the resin not injected into the cavity 27 is not cured in the runner 22a. The outer peripheral surface of the tip of the hot runner forming member 22 is formed in the center hole 1 to be formed in the substrate 13.
1 so that a projection 12 having a center hole 11 can be formed between the projection 12 and the fixed mold 21. On the other hand, the stamper 24 is formed by forming an inverted pattern in which the direction of the concavities and convexities is opposite to the signal pattern to be formed on the substrate 13 concentrically or spirally on the surface facing the fixed mold 21, Stamper positioning pin 2
5, the center of the reversal pattern is regulated, and the outer peripheral ring 26 holds the outer peripheral portion.
The central axis of the hot runner forming member 22 and the central axis of the stamper 24 are matched with high precision.

At the time of molding the substrate 13, first, as shown in FIG. 4, the runner 2 is placed in a cavity 27 formed by clamping the fixed mold 21 and the movable mold 23.
Inject resin from 2a. In this case, in order to improve the transferability of the signal pattern to the substrate 13, a compressive force can be applied to the resin filled in the cavity 27 at a required timing after the resin injection. After the resin in the cavity 27 has hardened, the movable mold 23 is opened from the fixed mold 21 as shown in FIG. At this time, the formed substrate 13
It is held on the movable mold 23 side by the action of the tapered surface 26 a formed on the outer peripheral ring 26. A runner 22 a is provided at the bottom of the center hole 11 of the formed substrate 13.
Trace 13a is formed. After opening the mold, as shown in FIG.
Remove 3. The take-out device 31 of this example is of a vacuum suction type, and includes an air chamber 31b in the substrate holding portion 31a and an O-ring 3 for sealing provided in an opening of the air chamber 31b.
1c and an air pipe 31d communicating with the air chamber 31b are provided. The O-ring 31c is pressed against the formed substrate 13 and the substrate 13 is sucked by driving a vacuum pump connected to the air pipe 31d. Then, the substrate 13 is taken out from the movable mold 23.

Next, as shown in FIG. 7, a reflection layer 1 is formed on the surface of the substrate 13 (the surface having no projections 12).
5, a recording layer 16 and a protective layer 17 are formed in this order. The reflection layer 15, the alloy-based recording layer 15, and the dielectric protection layer 17 can be formed by a vacuum deposition method such as vacuum evaporation or sputtering. On the other hand, an organic dye-based recording layer 16 and a resin-based protective layer 1 such as a UV resin are used.
7 can be formed by a spin coating method.
When the organic dye-based recording layer 16 and the resin-based protective layer 17 are formed by spin coating, a required film-forming material is dropped from a dispenser 32 disposed at the center of the substrate 13 as shown in FIG. You. Therefore, spin coating of a coating film can be performed more easily than when a film forming material is dropped from a dispenser on a substrate having a center hole formed on a recording layer forming surface.

Finally, as shown in FIG. 8, the substrate 13 on which the film has been formed is turned upside down and placed on the support 33 so that the substrate 1
A ring-shaped magnetic plate 14 is arranged concentrically with the projection 12 on the side of the projection forming surface 3. In this state, the tip of the projection 12 is locally deformed by pressing a horn (pressing portion) 34 of an ultrasonic welding device against the projection 12, and the tip of the deformed projection 12 is used as the magnetic plate 14. Is fixed to the substrate 13. Thus, the optical disk 10 shown in FIG. 1 can be obtained.

According to the optical disk manufacturing method of this embodiment, the fixed mold 21 having the fixed mirror 21a and the fixed mirror 21
a hot runner forming member 22 provided at the center of
And a movable mold 23 having a movable mirror 23a, a stamper 24, a stamper positioning pin 25, and an outer peripheral ring 26 disposed on the movable mirror 23a, and the fixed mirror 21a, the hot runner forming member 22, the stamper 24, Stamper positioning pin 25 and outer ring 26
The substrate is formed using a mold in which a cavity 27 for forming a substrate is formed by the hot runner forming member 2.
By forming the tip of the second part into a required shape, a signal pattern is formed on one side, and a substrate 13 integrally formed with a projection 12 having a center hole 11 on the other side can be manufactured. It is possible to easily manufacture the substrate 13 with projections in which the eccentricity between the tracks constituted by the arrangement and the center holes 11 is small. After molding the substrate 13 with the protrusions, the magnetic plate 14 is arranged on the surface of the substrate 13 on which the protrusions 12 are formed, and the substrate 13 and the magnetic plate 14 are integrated by partially deforming the protrusions 12. Therefore, it is not necessary to form a special member for fixing the magnetic plate 14 on the substrate, and the optical disk 10 of the magnet clamp type having a simple substrate structure and excellent appearance can be easily manufactured.

Next, the configuration of the drive device for recording, reproducing, or erasing information by mounting the optical disk 10 according to the embodiment, and the start-up performed by the drive device when the optical disk 10 is mounted on the drive device The operation will be described with reference to FIG. 9 and FIG. 3 described above. FIG. 9 is a flowchart showing the procedure of the start-up operation.

As shown in FIG. 3, the drive device for mounting the optical disk 10 according to the embodiment includes a spindle 6 inserted into a center hole 11 for centering the optical disk 10, and a spindle 6 fixed to the spindle 6. Turntable 7 for supporting the central area of optical disk 10
And a head carriage 8 disposed on a side facing the spindle 6 and the turntable 7 via the optical disc 10.
The optical head 5 transported in the radial direction of the optical disk 10 by the
7 for attracting the magnetic plate 14 provided in the
a provided with a. The spindle 6 can be constituted by a main shaft of a spindle motor (not shown). The diameter of the spindle 6 when inserted into the center hole 11 is such that the clearance between the inner diameter of the center hole 11 and the outer diameter of the spindle 6 is 5 μm to 10 μm. It is adjusted to become. As described above, since the drive device having the conventional structure shown in FIG. 11 can be used as the drive device on which the optical disk 10 according to the embodiment is mounted, it is not necessary to largely modify the drive device.

The start-up operation of the drive device will be described below with reference to FIG. 9. When the optical disk 10 is mounted on the spindle 6 and the turntable 7 (step S1).
The drive device checks whether or not the operation has been correctly performed (step S2). If it is determined in step S2 that the optical disk 10 has been correctly mounted, the drive device
The head carriage 8 is moved to the center of the optical disc 10 while maintaining the distance between the optical head 5 and the recording surface of the optical disc 10 (procedure S3), and a spindle motor (not shown) is activated (procedure S4), and the laser is turned on (procedure). S5) is performed. In step S5, the laser power is adjusted to the minimum power required for the focus servo of the optical head 5 in order to prevent the optical disk 10 from being damaged.

Next, while monitoring the focal position, the drive device gradually brings the optical head 5 and the optical disk 10 relatively closer to each other, and confirms that the focal length has entered the focus servo pull-in range. Is turned on, and the focus servo is controlled so that the laser spot irradiated from the optical head 5 is always focused on the recording film surface of the optical disk 10 (step S6).

Thereafter, the drive device moves the head carriage 8 to a desired recording / reproducing area on the optical disk 10 (step S7), and adjusts the laser power to the information reproducing level (step S8). As a result, the tracking servo is turned on (procedure S9), and the apparatus enters a command waiting state in which information can be recorded, reproduced, or erased (procedure S10).

By adopting such a start-up operation, the focus can be drawn in the central portion of the optical disk where the surface deflection is the smallest, so that the collision between the optical head 5 and the optical disk 10 can be avoided, and the first working distance is short. Surface-type optical disks can be used with confidence.

[0042]

According to the first aspect of the present invention, since the substrate is flattened from the center of the recording layer supporting surface to the outer peripheral portion, the central area of the optical disk which cannot be used as a conventional information recording area can be effectively used. Thus, the recording capacity of the optical disk can be increased and the disk size can be reduced.
Further, according to the first aspect of the invention, since the projection having the center hole is formed at the center of the surface of the substrate on which the recording layer is not carried, the track can be centered with high accuracy. Further, according to the first aspect of the present invention, since a projection having a center hole is formed at the center of the substrate, a conventional structure including a spindle and a turntable fixed to the spindle and supporting only the inner peripheral area of the optical disk. Can be mounted on the drive device, and it is not necessary to largely modify the drive device.

According to the second aspect of the present invention, since the diameter of the center hole formed in the substrate is set to 0.8 mm to 3 mm, the eccentricity between the center of the spindle and the center of the track is allowed while securing the rigidity of the spindle. It can be within the range.

According to the third aspect of the present invention, since the magnetic plate is provided on the surface of the substrate on which the protrusions are formed, it is possible to configure an optical disk of a magnet clamp system without reducing the recording area.

According to the fourth aspect of the present invention, since the magnetic plate for the magnet clamp is fixed by the protrusion formed on the substrate, it is not necessary to form a special member for fixing the magnetic plate on the substrate. A magnet-clamped optical disk which has a simple structure, is easy to manufacture, and has an excellent appearance can be constructed.

According to a fifth aspect of the present invention, there is provided a fixed mold having a fixed mirror, a hot runner forming member provided at a central portion of the fixed mirror, a movable mold having a movable mirror, and a movable mold having a movable mirror. A fixed mirror, a hot runner forming member, a stamper, a stamper, a mold for forming a cavity for forming a substrate with the outer ring, and a substrate. Since it is molded, by forming the tip of the hot runner forming member into a required shape, a signal pattern can be formed on one side, and a substrate having a projection having a center hole formed on the other side can be manufactured integrally. In addition, it is possible to easily manufacture a substrate having projections with small eccentricity between a track formed by an arrangement of signal patterns and a center hole. It is possible.

According to a sixth aspect of the present invention, after a substrate having projections is formed, a magnetic plate is disposed on the surface of the substrate on which the projections are formed, and a part of the projections is deformed to form the substrate and the magnetic plate. Since there is no need to form a special member for fixing the magnetic plate on the substrate, it is possible to easily manufacture a magnet clamp type optical disk having a simple substrate structure and excellent appearance.

[Brief description of the drawings]

FIG. 1 is a sectional view of an optical disc according to an embodiment.

FIG. 2 is a cross-sectional view of the optical disc showing a state of attachment to a drive device.

FIG. 3 is a cross-sectional view of the optical disc according to the embodiment in a used state.

FIG. 4 is a fragmentary cross-sectional view showing a step of injecting a resin into a cavity.

FIG. 5 is a fragmentary cross-sectional view showing a mold opening step after injection.

FIG. 6 is a fragmentary cross-sectional view showing a step of taking out the formed substrate.

FIG. 7 is a cross-sectional view showing a step of forming a recording layer and the like on a substrate surface.

FIG. 8 is a sectional view showing a step of attaching a magnetic plate to a substrate.

FIG. 9 is a flowchart illustrating a procedure of a start-up operation in the drive device.

FIG. 10 is a cross-sectional view showing a first example of an optical disk and a drive device according to a conventional example.

FIG. 11 is a sectional view showing a second example of the optical disk and the drive device according to the conventional example.

[Explanation of symbols]

 Reference Signs List 5 optical head 6 spindle 7 turntable 10 optical disk 11 center hole 12 protrusion 13 substrate 14 magnetic plate 15 reflective layer 16 recording layer 17 protective layer 21 fixed mold 21a fixed mirror 22 hot runner forming member 23 movable mold 23a movable mirror 24 stamper 25 Stamper positioning pin 26 Outer ring 27 Cavity

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G11B 7/26 521 G11B 7/26 521 (72) Inventor Fumiyoshi Kirino 1-88 Ushitora 1-chome, Ibaraki-shi, Osaka No. Hitachi Maxell, Ltd. (72) Inventor Nobuyuki Inaba 1-1-88 Ushitora, Ibaraki City, Osaka Prefecture Hitachi Maxell Co., Ltd. (72) Toshiaki Taii 1-1-88, Ushitora, Ibaraki City, Osaka Prefecture Hitachi Maxell Co., Ltd. (72) Inventor Yuji Yamazaki 1-88 Ushitora, Ibaraki-shi, Osaka F-term in Hitachi Maxell Co., Ltd. (Reference) 4F202 AG19 AG28 AH79 AR12 CA11 CB01 CK43 CK52 5D029 KB12 PA06 PA07 5D121 AA02 DD05 DD13 DD18 FF11 FF15

Claims (6)

[Claims] 1. An optical disk having a recording layer carried on one surface of a substrate, wherein a projection having a center hole is formed at the center of the surface of the substrate on which the recording layer is not carried;
An optical disc characterized by being flat from the center to the outer periphery of the surface of the substrate on which the recording layer is carried. 2. The optical disc according to claim 1, wherein
An optical disk, wherein the diameter of the center hole is formed in a range of 0.8 mm to 3 mm. 3. The optical disc according to claim 1, wherein
An optical disk, wherein a magnetic plate is provided on a surface of the substrate on which the protrusion is formed. 4. The optical disk according to claim 3, wherein
An optical disk, wherein the magnetic plate is fixed by a protrusion formed on the substrate. 5. A method for manufacturing an optical disk, wherein a resin is injected into a substrate molding die to form a substrate, and a recording layer is formed on one surface of the obtained substrate to obtain a required optical disk.
As the substrate molding die, a fixed die having a fixed mirror, a hot runner forming member provided at the center of the fixed mirror, a movable die having a movable mirror, and a movable die having a movable mirror were disposed on the movable mirror. A stamper, a stamper positioning pin, and an outer peripheral ring are provided, and the fixed mirror, the hot runner forming member, a mold in which a cavity for forming a substrate is formed by the stamper, the stamper positioning pin, and the outer peripheral ring are used. Injecting a resin into the cavity from the formed hot runner, transferring a signal pattern formed on the stamper to one surface, and obtaining a substrate having a projection having a center hole formed at the center of the other surface. A method of manufacturing an optical disc, characterized by: 6. The method for manufacturing an optical disk according to claim 5, wherein after obtaining the substrate, a magnetic plate is arranged on a surface of the substrate on which the protrusion is formed, and a part of the protrusion is deformed. A method for manufacturing an optical disk, comprising: integrating the substrate and the magnetic plate.